content: /* ===========================================================
   * JFreeChart : a free chart library for the Java(tm) platform
   * ===========================================================
   *
   * (C) Copyright 2000-2012, by Object Refinery Limited and Contributors.
   *
   * Project Info:  http://www.jfree.org/jfreechart/index.html
   *
   * This library is free software; you can redistribute it and/or modify it
   * under the terms of the GNU Lesser General Public License as published by
   * the Free Software Foundation; either version 2.1 of the License, or
   * (at your option) any later version.
   *
   * This library is distributed in the hope that it will be useful, but
   * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
   * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
   * License for more details.
   *
   * You should have received a copy of the GNU Lesser General Public
   * License along with this library; if not, write to the Free Software
   * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301,
   * USA.
   *
   * [Oracle and Java are registered trademarks of Oracle and/or its affiliates. 
   * Other names may be trademarks of their respective owners.]
   *
   * --------------
   * DialLayer.java
   * --------------
   * (C) Copyright 2006-2008, by Object Refinery Limited.
   *
   * Original Author:  David Gilbert (for Object Refinery Limited);
   * Contributor(s):   -;
   *
   * Changes
   * -------
   * 03-Nov-2006 : Version 1 (DG);
   *
   */
  
  package org.jfree.chart.plot.dial;
  
  import java.awt.Graphics2D;
  import java.awt.geom.Rectangle2D;
  import java.io.Serializable;
  import java.util.EventListener;
  
  /**
   * A dial layer draws itself within a reference frame.  The view frame is a
   * subset of the reference frame, and defines the area that is actually
   * visible.
   * <br><br>
   * Classes that implement this interface should be {@link Serializable},
   * otherwise chart serialization may fail.
   *
   * @since 1.0.7
   */
  public interface DialLayer {
  
      /**
       * Returns a flag that indicates whether or not the layer is visible.
       *
       * @return A boolean.
       */
      public boolean isVisible();
  
      /**
       * Registers a listener with this layer, so that it receives notification
       * of changes to this layer.
       *
       * @param listener  the listener.
       */
      public void addChangeListener(DialLayerChangeListener listener);
  
      /**
       * Deregisters a listener, so that it no longer receives notification of
       * changes to this layer.
       *
       * @param listener  the listener.
       */
      public void removeChangeListener(DialLayerChangeListener listener);
  
      /**
       * Returns <code>true</code> if the specified listener is currently
       * registered with the this layer.
       *
       * @param listener  the listener.
       *
       * @return A boolean.
       */
      public boolean hasListener(EventListener listener);
  
      /**
       * Returns <code>true</code> if the drawing should be clipped to the
       * dial window (which is defined by the {@link DialFrame}), and
       * <code>false</code> otherwise.
       *
       * @return A boolean.
       */
      public boolean isClippedToWindow();
  
      /**
       * Draws the content of this layer.
       *
       * @param g2  the graphics target (<code>null</code> not permitted).
       * @param plot  the plot (typically this should not be <code>null</code>,
       *     but for a layer that doesn't need to reference the plot, it may
       *     be permitted).
       * @param frame  the reference frame for the dial's geometry
       *     (<code>null</code> not permitted).  This is typically larger than
       *     the visible area of the dial (see the next parameter).
       * @param view  the visible area for the dial (<code>null</code> not
       *     permitted).
       */
      public void draw(Graphics2D g2, DialPlot plot, Rectangle2D frame,
              Rectangle2D view);
  
  }
  